Addiction is the product of three broad factors: Scott McMillan explains in a very good article

We develop habits and routines that seem to have a life of their own– and you’re never more aware of that than when you go to change them.

Someone in a discussion group was challenging people to ‘refute’ the research of this one scientist into the origins of addiction– in this instance, that it stemmed from childhood trauma. But I wondered why anyone would need to refute it?

A good theory should be inclusive enough to accommodate the available evidence. That’s not as easy as it sounds, because although research can provide results, it rarely provides clear, unequivocal answers. In practice, theory-building can be a bit like those civil trials where a verdict is obtained on the basis of ‘preponderance of evidence’ rather than the familiar crime TV standard, ‘beyond a reasonable doubt.’

Demanding absolute proof is how some otherwise reasonable folks are able to reject overwhelming scientific evidence for evolution or climate change. They simply insist it ain’t enough, because there’s still room left for doubt. To them, the word theory suggests something inconclusive, insubstantial. It’s grounds for rejection, regardless of how much science stands behind it.

If the majority of scientists had agreed, we’d never have landed on the Moon.

Anyway, as I see it, addiction is the product of three broad factors:

First is vulnerability (or if you prefer, susceptibility.) There’s strong evidence of a role for genetics, and also evidence that childhood trauma can contribute, as well as other trauma. Same for some forms of mental illness, and an assortment of other environmental factors. Because both nature and nurture are in play, we might expect to encounter individuals in whom one or the other side of the equation plays the dominant role. That seems to be the case with other complex disorders. I see no reason to expect addiction to be different.

Then there’s adaptation, or the complex process by which the brain, among other organs, adapts on a physiological level to the continuing presence of the substance. Tolerance and dependence are just two obvious examples, but fMRI scans suggest a much wider range of effects that contribute to addiction.

And of course, there’s the influence of behavioral conditioning, that process of reinforcement over months or years of use. We develop habits and routines that seem to have a life of their own– and you’re never more aware of that than when you go to change them.

My point: Research supports a role for all the above. So a good theory has to make room for all the evidence of valid, well-designed and replicated studies– as well as explain the experience of millions of sufferers. Anecdotal evidence isn’t inherently inferior. It’s different.

A good theory has to be amenable to modification as new evidence emerges. That’s how science works. And that’s a good thing.